The present invention relates to a tape cassette device in which is mounted an endless tape which magnetically records, for example, video signals and which is driven to travel at high speed.
For recording video signals on a magnetic recording tape and for reproducing them, the relative speed of the tape and the head mechanism must be high, for example, over 5 m/sec. Thus, for recording and reproducing video signals with a stationary head mechanism while driving the tape at a high speed, the tape must be made to travel at the above-mentioned high speed. This results in extremely increased consumption of the tape per unit time. In order to improve the efficiency of use of the tape, it is possible to arrange a number of tracks in the direction of the width of the tape. However, it is practically impossible to reverse the direction of tape travel at the end of the tape for sequential use of the tracks.
Thus, it has been proposed to arrange the tape so that it rotates in an endless manner and to set the direction of the tape travel in one particular direction while sequentially changing over the track after every full circle of the tape, so that the video signals may be recorded and reproduced over an extended period of time in a continuous manner.
A tape cassette device using an endless tape has been conventionally used for recording audio signals wherein a tape is wound on a reel for storage. The tape is drawn out from the inner periphery or the outer periphery of the wound portion for supplying it to the head mechanism of the recording and reproducing mechanism. In audio equipment, the tape is supplied to the outer periphery of the reel, and the recording and reproducing part and the tape drive mechanism are arranged at the end face of the cassette case enclosing the endless tape.
With such a construction, an opening may be formed at a position corresponding to one end face of the cassette, and the tape drawn out from the reel may be guided through this opening. Therefore, the cassette mechanism may be made simpler, and the structure of the head mechanism and the tape drive mechanism of the recording and reproducing mechanism of the cassette may be made simpler.
With this construction utilizing an endless tape, the device may be adopted for recording and reproducing audio signals at a tape speed of several centimeters per second. However, this construction is unsuitable for recording and reproducing video signals which require a tape speed of more than 5 meters per second, since this exerts too much load on the tape. Further, since the head mechanism and the drive mechanism for recording and reproduction are arranged outside the reel, the tape cassette is made larger in size so that the tape loading procedure becomes complex.
Considering this, it has been alternatively proposed to draw out the tape from the inner periphery of the reel and to arrange the head mechanism and the tape drive mechanism including the capstan and pinch roller inside the reel. According to this method, a ring-shaped reel is arranged in a fixed manner inside the cassette case, and part of the reel is notched away for forming a tape drawing window through which the tape at the inner periphery of the tape coil is drawn out. When the cassette is mounted on a recording and reproducing mechanism, the tape drive mechanism and the head mechanism at the cassette mounting surface of this mechanism are inserted through the cassette bottom plate into the stationary reel inside the cassette for driving the tape.
In an endless tape cassette of this type, a large opening is formed in the bottom plate at a position corresponding to the center of the stationary reel, and it is necessary to arrange roller holes at positions corresponding to the rollers in the recording and reproducing mechanism in a manner corresponding to the outer circumference of the reel and to support the tape mounted on the reel.
This means that the tape is encased and held inside a box body, while a large opening is formed in the bottom plate of the box body. Thus, in a tape cassette of this type, it is necessary to dispose a cover which effectively closes the opening formed in the bottom plate.
Moreover, the tape drawn to the center of the stationary reel is wound on the outer periphery of the reel. During this procedure, the tape may be loosened on the reel. When the tape is in this loosened condition on the reel, for mounting the cassette on the recording and reproducing mechanism, the tape may not be correctly loaded due to the relations among the space between the capstan and the pinch roller, the front surface of the head mechanism and the guide hole, resulting in complex handling of the tape cassette and irregular tape loading.